Electrical protective device.



A. W. COPLEY. ELECTRICAL PROTECTIVE DEVICE.

APPLICATION FILED DEC. 14. 1915.

Patented Dec. 26, E916.

WITNESSES: :NVENTOR 5M 4/70 4 W [op/6y ATTORNEY AL'MZON COPLEY, D1 WILKINSBURG, PENL'SYLVEHKA, A

ELECTRIC AND MANUFACTURING COMPAIETY, (582E01 ELECTRICAL PROTECTEVE 4;.

Application filed December 14, 1915.

T1 all whom it may, concern:

known that I, ALMoN W. Corner, a citizen of the United States, and a resident of ivilhinsburg, in the county of Alle- 5 ghcny and State of Pennsylvania, have in vented new and useful Improvement in Electrical Protective Devices, of which the- :following is a specification.

hfly invention relates to electrical-protective rev'ices and particularly to ,gneans for protecting electrical translating devices in accordance with the temperature thereof.

(inc object of my invention is to provide an electricLil-protective device that is actuatcd only when the temperature of the translating device to be protected reaches a predetermined value.

Another object of my invention is to provide a device of the above indicated charactor that shall operate correctly'irrespective of changes in the value of the electron'iotive force impressed upon the device.

Copending U. S. application Serial No. 53,867., filed September 21, 1915 by Charles LeGr. Fortescue, and assigned to the estinghouse Electric and Manufacturing Coinpany, discloses a resistor that is heated in accordance with the energy traversing a translating device. A constant -'potential circuit comprisinga battery and-an electroresponsive device is connected across equalpotential points of the resistor. WVhen the resistance of the resistor changes, because of a change in temperature, the current that traverses the electro-responsive device will vary substantially in accordance with variatic-11s in the temperature of the resistor. If: the resistor is sufficiently lagged that its heat emissivity, temperature gradient at current-s corresponding to given loads and the heat capacity are the same as the translating device, and, if the potential of the battery remains substantially constant, the electro-responsive device may be actuated in accordance with the temperature of the trans ating device. However, if the potential of the battery changes, the electroresponsive device may not function properly.

In order to preclude the improper functioning of the elcctro-res1:)onsive device, I

provide a resistor that is heated in accordance with the energy that traverses the translating device. I I provide also a Wheatstone bridge one arm of which comprlses the resistance of the resistor between the Specification of Letters Extent.

. Since the bridge is adap responsive minal. thereof. ed to such disconnect the sistance acros suiiicient to c become balance clectro responsi sponsive device m the operation of Pi an oil pump or any other prct d to he irrespective or the applied. clectro force, the elcctroaesponsive. w tion correctly under all balanced cow The single figure of the accon'in drawing is a d-"igranimatic illustrznv n of an electrical lating device that is ow tected by a relay system embodying vention.

An electrical circuit 1 is p o interrupter and a pri ary winds of a transformer 4- operat i thereto, the secondary winding is connected to an circuit 6. primary winding 7 of current titan or-inc? 8 is connected in circuit with the primary indingB of the transformer a, and the ondary winding oi. ransit'orincr are disposed in a. transformer tans" t ilGl'nPQfRtlllT-i thereof is substantially th "1? the transformer 4;. Ho 10 and 11 may he tank and be suiiicieni temperature to accordance with temperature of uno transformer 4.

A lVhcatstone hridege 13 comprises ti fgu d to cause i troinot-ive force and an clectro-iesponsive 3m vice 18. The resistors 14, and 16 constitute three arms of the bridge .13, the fourth arm constituting a circuit 19 c0m-- prising that part of the resistors 10 and 11 which is included between equal-potential points 20 and 21 thereof. The source 17 01*" electromotive force col iected two terminals of the bridge 1 and the electroresponsive device 18 connectr.' acr remaining terminals thereof.

lilo

responsive device 18 may consist of a conthe purpose or illustration, a plunger-type relay is here shown having a movable core member .22, a movable contact iiieinbe'i- 23 and stationary contact members The stationary contact members 2% are connected in a circuit comprising a source 26 of electroniotive force and the winding" 27 of a tripping elcctroinagnet 28 that is adaped to control the operation of the circuit interrupter When current traverses the primary winding 3 of the transformer a, a substantially proportional current traverses the resistors 1d and 11, and the resistance of the resistors 10 and 11 between the points 20 and 21 is so proportioned that, when the temperature of the transformer 4 reaches a predetermined value, the bridge 13 shall be balanced. When this a condition obtains, no current wiilv traverse the electro-responsive device 18 to thus permit the movable contact member 23 to engage the stationary contact members 2- to thereby close the circuit of the winding 27 of the tripping electroinagg net 28.

I desire it to be understood that my iiivention is not limited to the protection of tll'lSfOllIlei'S or the tripping of a circuit interrupter as it may be utilized for other purposes without departing from the spirit and scope of the invention as set forth in the appended claims.

I claim as my invention:

1. In a system of distribution, the combination with an electro-responsive device and a resistor adapted to be heated in accordancewith the current that traverses the system, of a plurality of resistors constituting three arms of a 'Vheatstone bridge, the fourt 1 arm of which comprises that part of the firstorrsntioncd resistor between equalpotentiai points thereof, the electro-responsive device being operatively connected to the bridge.

The combination with a translating de vice, a resistor adapted to be iii-aintaincd at a temperature corresponding to the temperature of the translating device, and an eiectroresponsive device, of a iVllQtli-SUHIQ bridge one arm of which constitutes that part of the resistor between eqiiahpotential points thereof, the electro-responsive device being operatively connected to the \Vheatstone bridge.

3. A protective system for a translating device comprising a resistor adapted to be maintained at a temperature proportional to prises that part of emma the temperature oi the translating device, a "Nheatstone bridge one arm of which comthe resistor between equalpotential. points thereof, and an electro-responsive device operativcly connected to the bridge and adapted to operate under predetermined conditions.

4:. The combination with a resistor, of a Wheatstone bridge one arm of which coinprises the resistance of the resistor between equal-potential points thereof.

5. In a protective system for a translating device. the combination with two parallelconnected resistors heated in accordance with the temperature of the translating device.' of a Wheatstone bridge. one arm of which comprises the resistance between two equahpotciitial points of and means adapted to be actuated by the unhaiancing of the current traversing the bridge.

6. The combination with two parallel-connected resistors, of a \Vheatstone bridge one arm of which comprises theresistance between two equal-potential 'ioints'ot tlie said resistors. i

7. The combination with a translating device and a protective-device therefor, of two parallel-connected resistors adapted to be maintained at a temperature proportional to the temperature of the translating device; a i heatstone bridge one arm of which co1nprises the resistance between two equal-potential points of the resistors. and an electroresponsive device operatively connected to the bridge and adapted to control the protective device.

h. The coi'nbination with a translating device and a resistor adapted to be maintained at a temperature correspondingto the temperature of the i Vheatstone bridge one arm of which (0111' prises the resistance between equal-potentiai points oi the resistor. 1

9. The combination with a translating device and a resistor adapted to be maintained at a temperature corresponding to thetemperature of the translating device, or". av

the said resistors,

translating device, of a i'i'heatstone bridge one arm of which comprises the resistance between equal-potential points of the resistor, and an electro-responsive device connected across two terminals of the bridge.

In testimony whereof, subscribed my name this 8th day of ALMOE. W. COPLEY.

1 have hereunto 1) cc. 

